fix(niri): let untitled Proton windows go fullscreen

XWayland/Proton windows can commit before they set a title. Excluding empty titles made Phantom Blade Zero miss the fullscreen rule and stay composited. Keep excluding the launcher announcement popup by title.

VRR is intentionally not enabled here: on-demand VRR caused display corruption in this game and is tracked separately.

Assisted-by: DeepSeek Harness (deepseek-flash)

home/linux/gui/niri/conf/windowrules.kdl

@@ -82,13 +82,11 @@ window-rule {
     // scale 1.5, so Niri's logical space is 2560x1440) cannot take over the
     // screen by itself.
     //
-    // The launcher shares this app id with the game, so the rule also catches
-    // its own windows: a helper that is still untitled while it maps, and the
-    // announcement popup (公告), which on this launcher renders as a pure white
-    // rectangle. Fullscreening either one buries the UI that opened it, so
-    // both are excluded here.
+    // Do not exclude empty titles here: XWayland/Proton windows can commit
+    // before they set a title, and excluding them would make the game miss
+    // this rule entirely and stay composited instead of going fullscreen.
+    // The launcher's announcement popup (公告) is still excluded by title.
     match app-id="^steam_app_[0-9]+$"
-    exclude title="^$"
     exclude title="^(公告|Announcement|Notice)$"
     open-on-workspace "4entertainment"
     open-fullscreen true